Click here for a list of all publications before retirement (in 2014).

**(2018)**
with Sergey Goryainov, Vladislav V. Kabanov and Leonid Shalaginov,

Deza graphs with parameters (n,k,k-1,a) and beta=1,
arXiv:1806.03462

**(2018)**
with S. Akbari, H.R. Maimani and L. Parsaei Majd,

Signed graphs cospectral with the path,
*
Linear Algebra and its Applications 553, * 104-116.

Also:
arXiv:1709.09853.

**(2018)**
with Aida Abiad and Steve Butler,

Graph switching, 2-ranks, and graphical Hadamard matrices,
arXiv:1801.01149

**(2018)**
with S.M. Cioaba, T. Johnston and M. McGinnis,

Cospectral mates for the union of some classes in the Johnson association scheme,
*
Linear Algebra and its Applications 539, * 219–228.

Also: arXiv:1701.08747.

**(2017)**
Spectral characterization of mixed extensions of small graphs,
*Discrete Mathematics * (to appear).

Also: arXiv:1712.01749.

**(2017)**
With S.M. Cioaba and J.D. Vermette,

The graphs with all but two eigenvalues equal to -2 or 0,
*
Designs Codes and Cryptography 84,* 153-163.

Also: arXiv:1601.05604.

**(2016)**
With Aida Abiad,

Switched symplectic graphs and their 2-ranks,
*
Designs Codes and Cryptography 81,* 35-41.

Also:
arXiv:1412.2945.

**(2016)**
With Hatice Topcu and Sezer Sorgun,

On the spectral characterization of pineapple graphs,
*
Linear Algebra and its Applications 507, * 267–273.

Also: arXiv:1511.08674.

**(2016)**
Are almost all graphs determined by their spectrum?

* Notices of the South African Mathematical Society /
Mededelings van die Suid-Afrikaanse Wiskundevereniging 47,* 42-45
(reprint).

**(2015)**
With A. Abiad and A.E. Brouwer,

Godsil-McKay switching and isomorphism,
*
Electronic Journal of Linear Algebra 28,* 4-11.

Also:
arXiv:1406.4170.

**(2015)**
With S.M. Cioaba, J.D. Vermette and W. Wong,

The graphs with all but two eigenvalues equal to ±1,
*
Journal of Algebraic Combinatorics 41,* 887-897.

Also:
arXiv:1310.6529.

**(2015)**
With Zoltan Blazsik and Jay Cummings,

Cospectral regular graphs with and without a perfect matching,
*Discrete Mathematics 338,* 199-201.

Also:
arXiv:1409.0630.

**(2014)**
With A.E. Brouwer, S.M. Cioaba and J.D. Vermette,

Notes on simplicial rook graphs,
*
Journal of Algebraic Combinatorics 43*, 783-799.

Also:
arXiv:1408.5615.

**(2014)**
With Marc Camara,

Spectral characterizations of almost complete graphs,
*
Discrete Appl. Math.176*, 19-23.

Also:
arXiv:1211.4420.

**(2014)**
With Edwin R. van Dam and Jack H. Koolen,

Regular graphs with maximal energy per vertex,
*
Journal of Combinatorial Theory, Series B 107*, 123-131.

Also:
arXiv:1210.8273.

**(2014)**
With Dean Crnkovic,

Walk regular divisible design graphs,
*
Designs Codes and Cryptography,*
*72*, 165-175.

Revision of: "more about divisible design graphs", CentER Discussion paper series Nr.: 2011-140,
Tilburg University.

**(2014)**
With A. Abiad, M.A. Fiol and G. Perarnau,

An Interlacing Approach for Bounding the Sum of Laplacian Eigenvalues of Graphs,
*
Linear Algebra and its Applications,
*
*448*, 11-21.

Also:
arXiv:1307.4670.

**(2012)**
With M.J.P. Peeters,

The maximum order of adjacency matrices with a given rank,
*
Designs Codes and Cryptography,*
* 65 *, 223-232.

Also:
CentER Discussion paper series Nr.: 2010-116,
Tilburg University.

**(2012)**
With Aida Abiad,

Cospectral Graphs and Regular Orthogonal Matrices of Level 2,
*Electronic Journal of Combinatorics* ,
Vol.19, Issue 3, P13.

Also:
CentER Discussion paper series Nr.: 2012-42,
Tilburg University.

**(2012)**
With Aart Blokhuis and Andries E. Brouwer,

The graph with spectrum
14^{1} 2^{40} (−4)^{10} (−6)^{9},
*
Designs Codes and Cryptography,*
* 65*, 71-75.

**(2012)**
Seidel switching and graph energy,
*
MATCH Commun. Math. Comput. Chem.*
*68*, 653-659.

Also:
CentER Discussion paper series Nr.: 2012-23,
Tilburg University.

**(2012)**
With M. Cavers, S.M. Cioaba, S. Fallat, D.A. Gregory, S.J. Kirkland, J.J. McDonald and M. Tsatsomeros

Skew-adjacency matrices of graphs,
*
Linear Algebra and its Applications 436*, 4512-4529.

**(2012)**
With M.J.P. Peeters,

The maximum order of reduced square (0,1)-matrices with a given rank,
*
Electronic Journal of Linear Algebra*
*24*, 3-6.

Also:
CentER Discussion paper series Nr.: 2011-113,
Tilburg University.

**(2011)**
With Edwin R. van Dam,

An odd characterization of the generalized odd graphs,
*
Journal of Combinatorial Theory, Series B 101*, 486–489
(reprint).

Also:
CentER Discussion paper series Nr.: 2010-47,
Tilburg University.

**(2011)**
With G.R. Omidi,

Universal adjacency matrices with two eigenvalues,
*
Linear Algebra and its Applications 435*, 2520-2529
(reprint).

Also:
CentER Discussion paper series Nr.: 2010-119,
Tilburg University.

**(2011)**
Matrices for graphs designs and codes
(Reader for the NATO workshop Information Security and Related Combinatorics, Opatija, Croatia, 2010).

In: Information Security, Coding Theory and Related Combinatorics
(D. Crnkovic and V. Tochev eds.),
IOSpress,
pp. 263-277 (reprint).

**(2011)**
With Hadi Kharaghani and Maaike A. Meulenberg,

Divisible design graphs,
*
J. Combinatorial Theory A 118*, 978-992
(reprint).

Also
CentER Discussion paper series Nr.: 2010-19,
Tilburg University.

**(2010)**
With Farzaneh Ramezani,

Graphs cospectral with Kneser graphs.
In:
Combinatorics and Graphs.
AMS. Contemporary Mathematics 531 (pp. 159-164).

Also:
CentER Discussion paper series Nr.: 2009-76,
Tilburg University.

**(2010)**
With Qing Xiang,

Strongly regular graphs with parameters
(4m^{4}, 2m^{4} + m^{2}, m^{4} + m^{2}, m^{4} + m^{2})
exist for all m>1,
*European Journal of Combinatorics 31*, 1553-1559
(reprint).

Also:
CentER Discussion paper series Nr.: 2008-86,
Tilburg University.

**(2010)**
With A. Mohammadian and B. Tayfeh-Rezaie,

On the Sum of Laplacian Eigenvalues of Graphs,
*
Linear Algebra and its Applications 432*, 2214-2221.

Also:
CentER Discussion paper series Nr.: 2008-98,
Tilburg University.

**(2009)**
Regularity and the spectra of graphs.

In:
Surveys in Combinatorics 2009,
Cambridge University Press,
London Mathematical Society Lecture Note Series No. 365 (pp. 75-90).
Preprint.

**(2009)** With E.R. van Dam,

Developments on spectral characterizations of graphs.
* Discrete Mathematics 309>*, 576-586
(reprint).

Also:
CentER Discussion paper series Nr.: 2007-33,
Tilburg University.

**(2009)**
With Sebastian Cioaba and David Gregory,

Matchings in regular graphs from eigenvalues,
*
Journal of Combinatorial Theory,
Series B 99*, 287-297 (reprint).

**(2008)**
With A.E. Brouwer,

The integral trees with spectral radius 3,
*
Linear Algebra and its Applications 429 *,2710'2718.

Also:
CentER Discussion paper series Nr.: 2007-84,
Tilburg University.

**(2008)**
Strongly regular graphs with maximal energy,
*
Linear Algebra and its Applications 429*, 2719'2723.

Also:
CentER Discussion paper series Nr.: 2007-37,
Tilburg University.

**(2008) **
With A.E. Brouwer,

Topics in algebraic graph theory,
Chapter 1 of
*
Lectures on Combinatorics I.
(G.B. Khosrovshahi ed.)*,
IPM, Lecture Notes Series 8 (pp. 1-66).

**(2008)**
With A.E. Brouwer,

A lower bound for the Laplacian eigenvalues of a graph - proof of a
conjecture by Guo,
*
Linear Algebra and its Applications 429*, 2131-2135.

Also:
CentER Discussion paper series Nr.: 2008-27,
Tilburg University.

**(2008)**
With A.E. Brouwer,

Hamiltonian strongly regular graphs,

CentER Discussion paper series Nr.: 2008-28,
Tilburg University.

**(2008)**With X. Liu and Y. Zhang,

Spectral characterizations of lollipop graphs,
*
Linear Algebra and its Applications
428*, 2415-2423.

**(2008)**With 17 coauthors,

Zero forcing sets and the minimum rank of graphs,
*
Linear Algebra and its Applications 428*, 1628-1648.
Preprint.

**(2007)**With A. Blokhuis and A.E. Brouwer,

On 3-chromatic distance-regular graphs,
*
Designs Codes and Cryptography 44*, 293-305
(reprint).

Also:
CentER Discussion paper series Nr.: 2006-120,
Tilburg University.

**(2007) **With E.R. van Dam and J.H. Koolen,

Cospectral graphs and the generalized adjacency matrix,
*
Linear Algebra and its Applications 423 *, 33-41.

Also:
CentER Discussion paper series Nr.: 2006-31,
Tilburg University.

**(2006) **With A.E. Brouwer, P.J. Cameron and D.A. Preece,

Self-dual, not self-polar.
*
Discrete Mathematics 306*, 3051-3053.
Preprint.

**(2006) **With N.C. Fiala,

5-Chromatic strongly regular graphs.
*
Discrete Mathematics 306*, 3083-3096.

Also:
CentER Discussion paper series Nr.: 2003-45, Tilburg University.

**(2006) **With E.R. van Dam, J.H. Koolen and E. Spence,

Characterizing distance-regularity of graphs by the spectrum.
*J. Combinatorial Theory A 113 *, 1805-1820.

Also:
CentER Discussion paper series Nr.: 2005-19,
Tilburg University.

**(2006) **With Andrey A. Chesnokov,

Regularity and the generalized adjacency spectra of graphs.
*
Linear Algebra and its Applications 416 *, 1033-1037.

Also:
CentER Discussion paper series Nr.: 2005-124,
Tilburg University.

**(2006) **Matrices and Graphs.
Chapter 28 of:
*
Handbook of Linear Algebra (L. Hogben ed.) *,

CRC Press, Chapman and Hall (pp. 28.1-28.13).

Also:
CentER Discussion paper series Nr.: 2005-37,
Tilburg University.

**(2005) **With A.E. Brouwer,

Eigenvalues and perfect matchings.
*
Linear Algebra and its Applications 395*, 155-162.

Also:
CentER Discussion paper series Nr.: 2004-58,
Tilburg University.

**(2005) **
Conditions for singular incidence matrices.
*
Journal of Algebraic Combinatorics 21*, 179-183.

Also:
CentER Discussion paper series Nr.: 2003-66,
Tilburg University.

**(2004) **With E. Spence,

Enumeration of cospectral graphs.
*
European Journal of Combinatorics 25*, 199-211.

Also:
CentER Discussion paper series Nr.: 2002-90, Tilburg University.

**(2003) **With E.R. van Dam,

Which graphs are determined by their spectrum?
*Linear Algebra and its Applications** 373*, 241-272.

Also:
CentER Discussion paper series Nr.: 2002-66, Tilburg University.

**(2003) **With E.R. van Dam and M.B.M. Peek,

Equitable resolvable coverings.
*
Journal of Combinatorial Designs 11,* 113-123.

Also:
CentER Discussion paper series Nr.: 2001-103, Tilburg Univerity.

**(2002) **With M. Doob,

The complement of the path is determined by its spectrum.
*Linear Algebra and its Applications** 356*, 57-65.
reprint.

**(2002) **With E. Kuijken,

The Hermitian two-graph and its code.
*Linear Algebra and its Applications** 356*, 79-93.

Also:
CentER Discussion paper series Nr.: 2001-83, Tilburg University.

**(2002) **With E.R. van Dam,

Spectral characterizations of some distance-regular graphs.
*
Journal of Algebraic Combinatorics 15*, 189-202.

Also:
Research Memorandum FEW 793, Tilburg University.

**(2001) **With E. Spence,

The pseudo-geometric graphs for generalized quadrangles of order (3,t).
*
European Journal of Combinatorics 22*, 839-845.

Also:
Research Memorandum FEW 794, Tilburg University.

**(2001) **Bicliques and eigenvalues. *
Journal of Combinatorial Theory, Series B 82*, 56-66.

Also:
Research Memorandum FEW 783, Tilburg University.

**(2001)** With A. Blokhuis,

An infinite family of quasi-symmetric designs. *Journal of
Statistical Planning and Inference 95*, 117-119.

**(2000)** With F.C. Bussemaker and E. Spence,

The search for pseudo orthogonal Latin squares of order six.
*
Designs Codes and Cryptography 21*, 77-82.

Also:
Research Memorandum FEW 780, Tilburg University.

**(1999)** With R. Peeters and J.M. van Rijckevorsel,

Binary codes of strongly regular graphs.
*
Designs Codes and Cryptography 17*, 187-209.

**(1999)** With M. Erickson, S. Fernando, D. Hardy and J. Hemmeter,

Deza graphs: A generalization of strongly regular graphs. *Journal
of Combinatorial Designs 7*, 395-405.

**(1999)** Minimum resolvable coverings with small parallel classes.
* Discrete Mathematics 197/198*, 393-396.

**(1998)** With E.R. van Dam,

Graphs with constant µ and µ-bar.
* Discrete Mathematics 182*, 293-307,

**(1997)** With A.E. Brouwer and V.D. Tonchev,

Embedding partial geometries in Steiner designs. In: J.W.P. Hirschfeld, S.S.
Magliveras and M.J. de Resmini (Eds.),

*Geometry, Combinatorial Designs and Related Structures*.
London Mathematical Society Lecture Note Series. 245,
Cambridge University Press (pp. 33-41).

**(1997)** With E.R. van Dam,

A characterization of distance-regular graphs with diameter three. *
Journal of Algebraic Combinatorics 6,* 299-303.

Spreads in strongly regular graphs.

Eigenvalues and the diameter of graphs.

Graphs cospectral with distance-regular graphs.

Quasi-symmetric designs related to the triangular graph.

Association schemes. Chapter 15 of :R. Graham, M. Grötschel and L. Lovasz (Eds.),

The Gewirtz graph - an exercise in the theory of graph spectra.

A design and a code invariant under the simple group Co3.